Gyrating screen



Aug. 20, 1963 R. A. DENOVAN v GYRATING SCREEN 2 Sheets-Sheet 1 Filed Oct. 24, 1960 I NVEN TOR 20, 1963 R. A. DENOVAN 3,101,315

GYRATING SCREEN Filed Oct. .24, 1960 2 Sheets-Sheet 2 Q Q II 354, FIG. 4

FIG 6 FIG. 7

INVENTOR BY W64, Q wk} I ATTQRNEY United States Patent 3,101,315 GYRATING SCREEN Robert A. Donovan, Dallreith, flntario, Canada, assignor to Denovan Ltd, Daikeith, Ontario, Canada, a corporation oi Canada Filed (let. 24, 1960, Ser. No. 64,374 2 Claims. (Cl. 2%9-832) This invention relates to screening mechanisms of the gyratory type.

Screen mechanisms of this type usually provide a screen body disposed at a slight angle ltO the horizontal and sloping downwardly from the head end to the discharge end thereof to cause the material being screened to flow in that direction under the agitation set up by motion imparted to .the screen body, which motion is circular at or near the head end and straight line lengthwise of the body at the discharge end.

In such a motion, the center of gravity moves lengthwise the full travel of the drive point of (the screen but crosswise less than the full travel, the proportion depending upon the position of the drive point. Thus, if the drive point is at thehead end, the crosswise travel of the center of gravity will be one-half the full travel of the drive point. Because of this characteristic, it is impossible to counter-balance the inertia forces of the screen by a simple counterweighted balance wheel.

It is highly desirable that a screening machine be free from obstructions under the screening surfaces for floor cleaning, servicing of the machine, location of discharge hoppers, and so forth. In many "locations it is also desirable that no part of the screen body supporting frame extend above the screen, and in all locations, it is very important that open bearings be at a minimum.

It is an object of this invention to provide a screening machine in which the screen body is effectively and simply counter-balanced during operation, in which the space above the screen body is completely unobstructed, and in which the space beneath the screen body is unobstructed to an effective degree.

The invention will be described with reference to the accompanying drawings, in which FIGURE 1 is a side elevation of a screening machine in accordance with the invention,

FIGURE 2 is an end elevation of the machine, certain parts being omitted for clarity of illustration,

FIGURE 3 is an enlarged side elevational view of a portion of the supporting frame,

FIGURE 4 is a sectional side elevation of the driving mechanism,

FIGURE 5 is a plan view of the driving mechanism,

FIGURES 6 and 7 are diagrammatic plan views of the counterbalancing arrangement,

FIGURE 8 is a plan view of an adjustable mounting means for a discharge end strut, and

FIGURE 9 is a side elevation of said adjustable mounting means.

Refenring to the drawings, the supporting frame comprises two posts 1 at the head end thereof and two posts 2 at the discharge end thereof. A guard rail 3 connects and supports each pair of posts 1 and 2, each rail 3 being inclined from the head to the discharge end. A diagonally extending side brace 4 connects each pair of posts 1 and 2 to provide required rigidity of frame.

A screen body 5 having a screening surface 5a and which may be of conventional form, is positioned between the guard rails 3.- The screen body is disposed at a slight angle to the horizontal and the inclined guard rails 3 will normally be in parallel relation to the screen body.

The discharge end of the screen body is resiliently Ice carried by two struts 6. Referring more particularly to FIG. 3, each strut 6 carries at its lower end a plate 7 seated on a cushion 8 of rubber or'like resilient material and mounted in socket member 9 carried by a foot member 10. Each strut 6 carries at its upper end a plate 11 seated on :a cushion 12 of rubber or the like material and mounted in a socket member 13 fixed to a bracket '14 mounted on the discharge end of the screen body. It will be appreciated that the dischange end struts 6 may be made for horizontal adjustment parallel to the length of the screen body, as indicated in FIGURE 3. It :has been found that the angle of strut relative to the screening surface of the body has an effect on screening function.

at one end thereof and engaging a rubber or like cushion 17 seated in bracket 18 fixed to the screen body at one side thereof. The link 15 also has a plate 19 at the other end thereof and engaging a rubber or like cushion Z0 seated in bracket 21 fixed to a post 2 adjacent the opposite side of the screen body.

At the head end of the screen body, the weight is carried by' a drive bearing connection 22 to be later referred to in greater detail. The head end of the screen body is stabilized by two cushioned struts 24 extending perpendicularly to the screen body and its screening surface and from the body to the supporting floor surface. Each strut 24 carries at its lower end a plate 25 seated on a cushion 2-6 of rubber or like resilient material and mounted in a socket member 27 fixed to a foot plate 28. Each strut 24 carries at its upper end a plate 29 bearing upon a rubber or like cushion 30 mounted in a socket member .31 fixed to the screen body. Each strut 24 since it carries substantially no load, may be adjustable as to length as by screw-threaded mounting thereon of the plate 29 in order to control the stabilizing function thereof. Similarly to struts 6, struts 24 have no bearings except by reason .of distortion of the resilient cushions thereof.

Driving means for the screen comprises a shaft 32 mounted under and perpendicularly to the screening sur face on bearings 33 in a housing 34 fixedvto posts 1 as by cross frame members 35. The upper end of the shaft is connected to (the screen body through drive bearings 22 which includes a crank member 36 fixed to the upper end of the shaft and on which is seated through suitable bearings a pivot block 37 mounted on the screen body. A similar type of drive bearing is illustrated in detail in prior United States Patent 2,705,561, dated April 5, 1955. e

The shaft 32 is [driven through a balance wheel 38 fixed thereto by rneans of belts 3 9 from the driving pulley 40 of a motor 41 also mounted on the cross frame 35. It will be apparent that revolution of the crank member 36 will impart a circular motion to the head end of the screen body.

Connteubalancing is effected by a compensated counterweight arrangement now to be described. A main counterweight 42 is mounted in the balance wheel 38 in opposed relation to the crank 36. A compensating smaller counterweight 43, preferably having a smaller radius of revolution, is mounted on a housing 44 revolvably mounted on shaft 32 by means of bearings 45. To the lower end of housing 44 is fixed a ring bevel gear 45 which is driven :by shaft 32 but in an opposite direction thereto by a ring bevel gear 47 fixed to the lower end of the shaft and an idle bevel pinion 48 mounted on a shaft '49 supported by housing 34.

It will be apparent that the housing 34 also constitutes a gear box which houses the compensating counterweight 43 and its driving gears.

An oil circulating device may be provided in the gear box and, as shown, comprises an oil fiinger disc 59* mounted on shaft 49 for rotation therewith and a housing 51 surrounding the disc. Housing 51 has axial openings 52 and 53 and a top outlet 64. A projection 55 on the main housing whereby oil from the oil fiinger thrown against such surface will be deflected into the space between the two bearings thus lubricating both.

Means are preferably provided for adjusting the angle of the discharge struts 6. This is an important feature of the invention since this angle and the consequent vertical component of the motion of the screen body at the discharge end has a marked efifect'on the screening efiiciency.

A means of providing such adjustment is illustrated in FIGURES 8 and 9 and comprises a foot plate 58 mounted for adjustment in a forward or rearward direction on a floor plate 59 by means of clamping bolts 60 which extend through slots 61 in the foot plate. The socket member 9 of the strut 6 is carried by the foot plate, as shown.

The counterbalancing weights 42 and 43 are such that, when in overlying relation as shown in FIGURE 6, they counter the longitudinal inertia of the screen body and, when in radially opposed relation as shown in FIGURE 7 they counter the crosswise inertia of the screen body. As the weights revolve in opposite directions, they are together and opposite twice in each revolution; hence, if synchronized with the screening motion, the result will be that the screen is properly counter-balanced in all positions.

An important feature of the invention resides in the :fact that the screen body and the main counterbalancing Wheel 38 are driven directly from the motor and that the compensating system is fully enclosed in the gear box 34'. Thus, drive adjustments such as speed are readily madeand only one shaft neck bearing is required instead of additional pinion shaft bearings and oil seals as in the case where the power is supplied through a pinion and gears. In the present instance, the pinion and gears drive the compensating balance weights only.

As previously indicated, the entire space above the screen body is free from obstruction. Moreover, since the supporting frame consists of four posts with cross members and only one diagonal brace on each side thereofwhich, in conjunction with the guard rails parallel to the screen body, constitutes a rigid and effective support, there is no actual obstruction to floor cleaning or servicing of the machine itself. Since there is only one bearing outside of the gear box, namely, the main screen drive bearing, it is very efiectively dust-protected.

Since, in operation, all articulation resides in the distortion of the resilient cushions, there are no rubbing surfaces.

In asbestos rnlling, it is highly important that no grease or oil gets into the fibers, hence the added importance of no outside bearings and, in -fact, of no horizontal shafts having seals from which grease might leak. It will be observed that, in the described structure, a grease-dust seal '57 is provided in the neck bearing 33 separate from the bearing lubricating system.

I claim:

1. A gyrating screen machine comprising, a base, an inclined screen body having a screening surface, a head end, and :a discharge end, means located wholly below said body for imparting gyratory movement thereto, comprising a driven shaft, a balance wheel fixed to said shaft, a crank on said balance wheel and a drive bearing connecting said crank to said body, said drive bearing constituting a support for said head end, a supporting frame comprising a pair of posts at each end of said body, said movement imparting means being carried by said pair of posts at said head end, a pair of stabiliz ng struts for said head end, each extending substantially perpendicularly downward from said body, each said strut having a lower end and an upper end, a seat for the lower end of each said strut, mounted on said base, a seat for the upper end of each said strut, mounted on said body, a resilient cushion carried by each said end of each said strut, a cushion being interposed between one said strut end and one said seat for each strut, said seat for said lower end of each said supporting strut being adjustable relatively to said base to vary the angularity of each said strut relatively to said base, said supporting frame being wholly located below said top screening surface whereby said surface is unobstructed, a main counterweight carried by said balance wheel, a compensating counterweight mounted for revolution about the axis of said shaft and having a smaller circumference of revolution than that of said main counterweight, and gear means connected to said shaft for driving said compensating counterweight in a direction opposite to the direction of rotation of said shaft and main counterweight.

2. A gyrating screen machine as defined in claim 1, said compensating counterweight and said gear means being disposed below said balance wheel, and a gear box surrounding said shaft and enclosing said compensating counterweight and said gear means.

References Cited in the file of this patent UNITED STATES PATENTS 1,265,267 Simpson May 7, 1918 1,411,834 Bland Apr. 4, 1922 1,668,984 Simpson May 8, 1928 1,675,560 Jubien July 3, 1928 2,194,721 Piper Mar. 26, 1940 2,248,182 Maiteer July 8, 1941 2,705,561 Denovan Apr. 5, 1955 2,819,796 Edwards Ian. 14, 1958 FOREIGN PATENTS 477,949 Great Britain Dec. 29, 1937 640,839 Great Britain July 26, 19 50 

1. A GYRATING SCREEN MACHINE COMPRISING, A BASE, AN INCLINED SCREEN BODY HAVING A SCREENING SURFACE, A HEAD END, AND A DISCHARGE END, MEANS LOCATED WHOLLY BELOW SAID BODY FOR IMPARTING GYRATORY MOVEMENT THERETO, COMPRISING A DRIVEN SHAFT, A BALANCE WHEEL FIXED TO SAID SHAFT, A CRANK ON SAID BALANCE WHEEL AND DRIVE BEARING CONNECTING SAID CRANK TO SAID BODY, SAID DRIVE BEARING CONSTITUTING A SUPPORT FOR SAID HEAD END, A SUPPORTING FRAME COMPRISING A PAIR OF POSTS AT EACH END OF SAID BODY, SAID MOVEMENT IMPARTING MEANS BEING CARRIED BY SAID PAIR OF POSTS AT SAID HEAD END, A PAIR OF STABILIZING STRUTS FOR SAID HEAD END, EACH EXTENDING SUBSTANTIALLY PERPENDICULARLY DOWNWARD FROM SAID BODY, EACH SAID STRUT HAVING A LOWER END AND AN UPPER END, A SEAT FOR THE LOWER END OF EACH OF SAID STRUT, MOUNTED ON SAID BASE, A SEAT FOR THE UPPER END OF EACH SAID STRUT, MOUNTED ON SAID BODY, A RESILIENT CUSHION CARRIED BY EACH SAID END OF EACH SAID STRUT, A SUCHION BEING INTERPOSED BETWEEN ONE SAID STRUT END AND ONE SAID SEAT FOR EACH STRUT, SAID SEAT FOR SAID LOWER END OF EACH SAID SUPPORTING STRUT BEING ADJUSTABLE RELATIVELY TO SAID BASE TO VARY THE ANGULARITY OF EACH SAID STRUT RELATIVELY TO SAID BASE, SAID SUPPORTING FRAME BEING WHOLLY LOCATED BELOW SAID TOP SCREENING SURFACE WHEREBY SAID SURFACE IS UNOBSTRUCTED, A MAIN COUNTERWEIGHT CARRIED BY SAID BALANCE WHEEL, A COMPENSATING COUNTERWEIGHT MOUNTED FOR REVOLUTION ABOUT THE AXIS OF SAID SHAFT AND HAVING A SMALLER CIRCUMFERENCE OF REVOLUTION THAN THAT OF SAID MAIN COUNTERWEIGHT, AND GEAR MEANS CONNECTED TO SAID SHAFT FOR DRIVING SAID COMPENSATING COUNTERWEIGHT IN A DIRECTION OPPOSITE TO THE DIRECTION OF ROTATION OF SAID SHAFT AND MAIN COUNTERWEIGHT. 